The present invention relates to a biometric system, and particularly to a biometric system for improving capture of a human characteristic by a biometric sensor. The invention also relates to a self-service terminal incorporating such a biometric system.
Biometrics is the measurement of some physical or biological trait or characteristic pertaining to an individual for use in confirming or determining the individual's identity.
Biometric systems are typically used in applications where secure access is required. Secure access may relate to physical locations (such as parts of a building), electronic devices and systems (such as automated teller machines, cellular telephones, personal computers), and software applications.
Secure access may be provided by a user typing in data, such as login codes or passwords. However, these can be compromised relatively easily if a third party becomes aware of the data to be typed in. Secure access may also be provided by identification card and personal identification number (PIN) combinations, such as is commonly required at automated teller machines (ATMs). However, this can also be compromised if the card details and the PIN are obtained by a third party.
Biometric systems have the advantage that a trait of an individual is measured to determine if that individual should be allowed access to a secure area or device. This makes it much more difficult for a third party to gain access because no memory based data entry occurs. However, biometric systems have the disadvantage that it is relatively difficult to obtain an accurate reading from an individual, particularly if the individual is a member of the public who has not been trained in how to use the biometric system, and if the system is used in an unattended environment.
One example of an application where biometric systems are used with members of the public is ATMs. An ATM is a particular type of self-service terminal (SST). SSTs are generally public-access devices that are designed to allow a user to conduct a transaction or to access information in an unassisted manner and/or in an unattended environment. SSTs typically include some form of tamper resistance so that they are inherently resilient. SSTs allow users to obtain information or to conduct a transaction, and include: ATMs; non-cash kiosks that allow users to access information (for example, to view reward points on a reward card the user inserts into the SST); and kiosks that accept payment for services (for example, Web surfing kiosks, kiosks that allow users to buy goods, and such like). The term SST has a relatively broad meaning and includes vending machines.
Biometric systems operate by initially obtaining one or more biometric measurements from a given subject, which might be an iris scan, a finger print or the like. Typically these initial measurements are compressed into a smaller form know as a template, which is stored in a database or local storage medium, such as a Smart card from which it can be retrieved at a later time.
A major problem in operating a biometric system lies in the accurate capture of a suitable enrolment image. Therefore, the original enrolment phase is critical to the subsequent performance of the biometric system. If a poor quality enrolment image is introduced into the system then the subsequent template generated will only contain a limited number of unique markers that identify that individual. This can lead to two undesirable situations. Firstly, with only a limited number of unique identifiers to match against, the individual may not be successfully identified when they come to provide a subsequent verification image. This is known as a false negative or false reject. Similarly with said limited number of unique identifiers available a potential attacker, who has a similar style of biometric measurement, may be accepted by a biometric system, which is known as a false positive or false acceptance.